1. Technical Field
The invention relates generally to wireless communication systems; and more particularly to a system and associated of operation for distributing load among mobile switching centers supporting a wireless network.
2. Related art
Wireless communication systems are generally known in the art to service wireless communications within a service area. The construction of a wireless communication system typically includes a plurality of base stations dispersed throughout the service area. The base stations couple to base station controllers, with each base station controller serving a plurality of base stations. Each base station controller couples to a mobile switching center that also couples to the public switched telephone network and to other mobile switching centers. Mobile units operating within the wireless communication system establish communication with one or more of the base stations. The structure of the wireless communication system is hierarchical such that the load served by the base stations routes through a predetermined path via a designated base station controller to a designated mobile switching center.
When the resources of the wireless communication system are insufficient to service load in a particular area, not all requested calls will be serviced. The capacity shortfall causes calls to be dropped, calls to be blocked and degrades system performance. Failing to service customers results in the loss of customers as well as a reduction in the revenue that would otherwise be generated by servicing the calls. Thus, it is extremely important to support as many calls as possible so that subscribers remain with the service provider and so that revenues are maximized.
When a wireless communication system is first deployed, base stations are located to provide wireless coverage throughout the service area. In a typical installation, each base station will be assigned to a geographic area of an approximately equal size. However, in areas of greater load density, base stations are placed closer to one another than in areas of lesser load density to increase the capacity of the wireless communication system in such areas. Load density depends upon a number of things, including population density, penetration rates, cost of service and various other factors that determine a concentration of subscribers that use their wireless units to service calls at any particular time. Load density may be predicted based upon both simulations and historical load usage patterns.
For example, in a metropolitan area such as the greater Dallas area, load density is greater in the downtown area, particularly during the day. However, in the evening and at night when the people that work downtown commute to the outlying areas, the load density downtown decreases. The inverse effect is seen in the outlying areas surrounding the downtown area. With a large work force located downtown during the day, traffic on the outlying areas is reduced. However, as the work force drives home from the downtown area into the outlying areas, load increases in the outlying areas. Thus, load varies over time not only in the downtown area but in the outlying areas as well.
Unfortunately, the capacity of the installed wireless communication system is fixed over time. Thus, to have a capacity sufficient to service a large number of calls within any portion of the service area during a peak loading period, significant resources must be installed across the service area. Such resources are extremely expensive and, when not fully used to service calls, generate no revenue for the service provider. Thus, in most systems, resources are deployed based upon expected load patterns initially and expansions are made to provide additional capacity to those areas that are overloaded. While such expansions may provide an immediate solution to the problem, the expansions are expensive as well and are only utilized during heaviest loading periods.
Thus, there is a need in the art for a wireless communication system and method of operation that manages resources to provide capacity in those portions of the wireless communication system requiring capacity when needed, but that may reassign the resources to other portions of the wireless communication system when the resources are required elsewhere. Further, there is a need in the art for a method for allocating such resources to optimally load the wireless communication system.